Indo-Pacific bottlenose dolphin (Tursiops aduncus) habitat preference in a heterogeneous, urban, coastal environment

Abstract

BackgroundLimited information is available regarding the habitat preference of the Indo-Pacific bottlenose dolphin (Tursiops aduncus) in South Australian estuarine environments. The need to overcome this paucity of information is crucial for management and conservation initiatives. This preliminary study investigates the space-time patterns of habitat preference by the Indo-Pacific bottlenose dolphin in the Port Adelaide River-Barker Inlet estuary, a South Australian, urbanised, coastal environment. More specifically, the study aim was to identify a potential preference between bare sand substrate and seagrass beds, the two habitat types present in this environment, through the resighting frequency of recognisable individual dolphins.ResultsPhoto-identification surveys covering the 118 km2 sanctuary area were conducted over 2 survey periods May to August 2006 and from March 2009 to February 2010. Sighting frequency of recognisable individual Indo-Pacific bottlenose dolphins established a significant preference for the bare sand habitat. More specifically, 72 and 18% of the individuals sighted at least on two occasions were observed in the bare sand and seagrass habitats respectively. This trend was consistently observed at both seasonal and annual scales, suggesting a consistency in the distinct use of these two habitats.ConclusionsIt is anticipated that these results will benefit the further development of management and conservation strategies.

New Evidence for Bottlenose Dolphin (Tursiops spp.) Population Connectivity between Kangaroo Island and South Australian Mainland Waters

“…occur [28] [29]. Both of these habitat types represent important areas utilised by dolphins in this area [4]. Secondly, Victor Harbor is located on the western side of Encounter Bay, a large shallow and sheltered embayment where Southern right whales, Eubalaena australis, are recurrently observed forming aggregations [30]; both unaccompanied individuals and females typically return annually to these nearshore waters to give birth, raise young, and socialize [30] [31].…”

“…are found globally throughout temperate and tropical seas, and are frequently observed in shallow coastal habitats as well as offshore oceanic waters [1]. This species is commonly occurring in South Australian waters [2] [3] [4]. Baseline information regarding the ecology, distribution and movements on this species and the potential connectivity between local populations in this region is, however, still very limited, with most information based upon stranding records [2] [3].…”

“…Baseline information regarding the ecology, distribution and movements on this species and the potential connectivity between local populations in this region is, however, still very limited, with most information based upon stranding records [2] [3]. However, previous studies have provided evidence of bottlenose dolphins occurring within both Spencer and Gulf St. Vincent as well as in the vicinity of Adelaide [5] [6] [7] and in particular the Port River-Barker Inlet estuary (The Adelaide Dolphin Sanctuary) where they are known to be resident all year round [4] [5].…”

“…Information on the movements of individuals between populations is crucial to the understanding of their space-time preference and use of specific locations [4]. Providing evidence of such movements and the use of specific locations is therefore the first stage in establishing and implementing effective management strategies [8].…”

“…In particular, this technique has been applied to examine the ecology, behavior and movement patterns of cetaceans [11] [12]. More specifically, the application of this technique has provided insight into the movements and distribution of bottlenose dolphins in numerous locations at the global scale [4] [13] [14] [15]. Photoidentification of bottlenose dolphins is used to identify individuals non-invasively by using distinctive dorsal fin features, for example nicks and notches present on both the trailing and leading edges of the fin and tip [16] [17].…”